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TRPM4 impacts on Ca2+ signals during agonist-induced insulin secretion in pancreatic beta-cells

V Marigo1, K Courville, W H Hsu

  • 1Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA.

Molecular and Cellular Endocrinology
|December 10, 2008
PubMed

Insights

Transient Receptor Potential Melastatin 4 (TRPM4) channels facilitate cell depolarization, crucial for insulin secretion in pancreatic beta-cells. Their inhibition significantly reduces calcium signals and insulin release, highlighting TRPM4

Area of Science:

  • Endocrinology
  • Cell Physiology
  • Molecular Biology

Background:

  • Transient Receptor Potential Melastatin 4 (TRPM4) is a calcium (Ca2+)-activated non-selective cation channel.
  • TRPM4 plays a role in cell depolarization, influencing calcium influx and insulin secretion in pancreatic beta-cells.

Purpose of the Study:

  • To investigate the expression and function of TRPM4 in various pancreatic alpha- and beta-cell lines.
  • To determine the role of TRPM4 in regulating intracellular calcium levels and insulin secretion.

Main Methods:

  • Reverse transcription polymerase chain reaction (RT-PCR) to detect TRPM4 transcripts.
  • Patch-clamp electrophysiology to measure TRPM4 channel activity and cell depolarization.
  • Calcium (Ca2+) imaging to assess intracellular calcium dynamics and agonist-stimulated signals.
  • Dominant-negative inhibition of TRPM4 to evaluate its functional impact.

Main Results:

  • TRPM4 transcripts were identified in both alpha- and beta-cell lines (HIT-T15, RINm5F, beta-TC3, MIN-6, INR1G9).
  • Patch-clamp recordings showed a dose-dependent activation of TRPM4 by increasing calcium concentrations, with the strongest currents in hamster cells.
  • Inhibition of TRPM4 significantly reduced agonist-stimulated intracellular calcium signals.
  • Reduced intracellular calcium levels correlated with decreased insulin secretion.

Conclusions:

  • TRPM4 channels are expressed in pancreatic alpha- and beta-cells.
  • TRPM4-mediated depolarizing currents are critical for controlling intracellular calcium signals necessary for insulin secretion.
  • TRPM4 may also play a role in glucagon secretion from alpha-cells.

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